Trailer Wiring

[cgriffith]

The factory hitch and wiring comes with a 4 connector wiring. Trailers now have 5 connectors with the 5th wire allowing the trailer to be backed up. The fifth wire overrides the solenoid in the trailer hitch. I had to stick a screwdriver in the hitch to override it and get back in the stall. I have a kit to convert to 5, but it should be wired into the backup lights. My dealer won't do it and the manual says if you monkey with the wiring you void the warranty. I'm wondering given the backup lights are LED if there is enough power for what the trailer needs. A friend said you could hook into the tail lights and just turn on the lights when you need to back up, but they look to be LED also.

any thoughts

 

[alexdrums]

Do LED lights need more power? I thought they used less energy.

 

[cgriffith]

I looked inside the boot going into the tail gate and there are over 10 wires, some are very small, I'm thinking the LED use less power so maybe they downsized the wires. If I could find the right wire??? to the LED back-up lights, maybe the power would not be enough to work the trailer and or cause other problems?

 

[alexdrums]

IMHO you would be better off not messing with the installed wiring. Go to one of the larger U-Haul stores and get them to install a hard-wired 7-pin connector. They have been doing it forever and can make any car tow. If you don’t want to spend the money, there is a video of a guy on YouTube who installed the 7-pin with a brake controller on his Telluride. But it is a really involved install and not for the feint of heart.

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[KTEL892]

I looked inside the boot going into the tail gate and there are over 10 wires, some are very small, I'm thinking the LED use less power so maybe they downsized the wires. If I could find the right wire??? to the LED back-up lights, maybe the power would not be enough to work the trailer and or cause other problems?

I saw somewhere on this forum a pinout diagram of the connector behind the left rear tire for the four pin trailerconnector for

I looked inside the boot going into the tail gate and there are over 10 wires, some are very small, I'm thinking the LED use less power so maybe they downsized the wires. If I could find the right wire??? to the LED back-up lights, maybe the power would not be enough to work the trailer and or cause other problems?

I saw somewhere on this forum a pinout diagram for the under vehicle trailer connector behind the left rear tire that extends to the 4 pin trailer plug. I think that the backup light was terminal 8, there were maybe 10 pins, all were not used. Would not be difficult to tap.

 

[cgriffith]

My trailer has surge brakes so when I plug the 5 connector from the trailer to the car's 4 pin, all works good (brake lights, turn signals, running lights) except for the missing 5th connector which allows the trailer to back up. The 7 pin enables electric brakes which I don't need. I had a Tahoe and it comes factory 7 pin and I needed a conversion from 7 pin to 5 pin for the trailer.
I'll check with U-haul, and look at the video, but I'm guessing they splice into the existing wiring.

 

[cgriffith]

I saw somewhere on this forum a pinout diagram of the connector behind the left rear tire for the four pin trailerconnector for

I saw somewhere on this forum a pinout diagram for the under vehicle trailer connector behind the left rear tire that extends to the 4 pin trailer plug. I think that the backup light was terminal 8, there were maybe 10 pins, all were not used. Would not be difficult to tap.

 

[cgriffith]

Great I found it. Robabco post 11/27/2019.
I will try this and let everyone know.
I bought the kit for a few bucks that adds the 5th wire from etrailer.

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[alexdrums]

My trailer has surge brakes so when I plug the 5 connector from the trailer to the car's 4 pin, all works good (brake lights, turn signals, running lights) except for the missing 5th connector which allows the trailer to back up. The 7 pin enables electric brakes which I don't need. I had a Tahoe and it comes factory 7 pin and I needed a conversion from 7 pin to 5 pin for the trailer.
I'll check with U-haul, and look at the video, but I'm guessing they splice into the existing wiring.

I didn’t know about the 5-pin connector, that is cool.

 

[mshabana]

IMHO you would be better off not messing with the installed wiring. Go to one of the larger U-Haul stores and get them to install a hard-wired 7-pin connector. They have been doing it forever and can make any car tow. If you don’t want to spend the money, there is a video of a guy on YouTube who installed the 7-pin with a brake controller on his Telluride. But it is a really involved install and not for the feint of heart.

I completely agree and I want to do just that but I still haven't found out if doing that voids the warranty or not?

 

[alexdrums]

You would be adding completely new wiring, so it couldn’t void the warranty.

 

[jw_tx21]

I completely agree and I want to do just that but I still haven't found out if doing that voids the warranty or not?

Since 1975, this hasn't been an issue. See this explanation from the FTC. There was a whole discussion on this issue in the forum - search Magnuson-Moss

Auto Warranties and Service Contracts

If you're buying a new or used car, the salesperson might try to sell you an auto service contract to help protect against unexpected or expensive repairs.

www.consumer.ftc.gov

Bottom line is that if you don't damage a part that is covered under warranty during installation of your aftermarket devices, then the manufacturer couldn't deny the warranty. Long term, it may be best to have something professionally installed if necessary so you have a paper trail. But, for towing, you need to make whatever modifications you need to tow safely - the Telluride even with the tow package isn't equipped out the door to handle towing 5,000 lb safely - despite Kia's ads. They know this.

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[alexdrums]

Good info, JW!

 

[cgriffith]

The factory hitch and wiring comes with a 4 connector wiring. Trailers now have 5 connectors with the 5th wire allowing the trailer to be backed up. The fifth wire overrides the solenoid in the trailer hitch. I had to stick a screwdriver in the hitch to override it and get back in the stall. I have a kit to convert to 5, but it should be wired into the backup lights. My dealer won't do it and the manual says if you monkey with the wiring you void the warranty. I'm wondering given the backup lights are LED if there is enough power for what the trailer needs. A friend said you could hook into the tail lights and just turn on the lights when you need to back up, but they look to be LED also.

any thoughts

 

[cgriffith]

The debris cover is shown below that is at the left rear. Comes off easy. In the big pic, you can see where the main harness connects to the one with the red and white wires which then goes to a sealed connector, that then goes out to the hitch's current 4 pin connector. Couple of closer pics attached. It would be sweet if one of the ones coming out of the main harness was the 5th wire for backup. I can check, but don't have my tester at this location.

 

[KTEL892]

The debris cover is shown below that is at the left rear. Comes off easy. In the big pic, you can see where the main harness connects to the one with the red and white wires which then goes to a sealed connector, that then goes out to the hitch's current 4 pin connector. Couple of closer pics attached. It would be sweet if one of the ones coming out of the main harness was the 5th wire for backup. I can check, but don't have my tester at this location.

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[KTEL892]

Pinout diagram was posted last November, Backup light is Pin 8

The backup light signal is available in the 12-pin harness for the tow hitch. It is pin 8 (see below). The tow harness is located behind the debris cover behind the left rear wheel - just follow the tow hitch harness if you have the factory hitch installed. The factory hitch has a four blade connector, but it has a metal plate that can be removed where the connector is installed that can be removed so a 7-pin round connector can be installed. Unfortunately, there is no pre-installed wiring for a trailer brake, so if needed, you will need to install a TB and run the appropriate wiring.

 

[alexdrums]

So will the backup light signal on Pin 8 activate the backup lights and release a trailer’s surge brakes?

 

[KTEL892]

So will the backup light signal on Pin 8 activate the backup lights and release a trailer’s surge brakes?

Yes, back up light signal on 5 pin trailer connector energizes solenoid valve on trailer so trailer disc brakes are not engaged when reversing. (Not necessary with drum brakes on trailer)

 

[alexdrums]

Great info, thanks!